Pneumatic slack-adjuster.



C. P. CASS.

PNBUMATIC sLAcK ADJUSTER. APPLIOATION TILED JULY 25, 1911.

1,055/144, Patented Mar. 11, 1913.

Ah Tay UNITED STATES' PATENT' OFEICE.

CHRISTOPHER P. CASS, OFMAELEWOOD, MISSOURI, ,SSIGNOR TO THE WESTINGHOUSE AIR BRAKE COMPANY, 'OF PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F Specification of Letters-Patent.

PNEUMATICI SLAGK-ADJUSTER. i

Patented Mar. 11, 1913.

Application led July 25, 1911.y Serial No. 640,490.

State of Missouri, have invented ne\' and useful Improvements in Pneumatic Slack- Adjust-ers, of which the folloivingisa specification.

This invention relates to fluid pressure binkes, and moie,particularly to a slack adjusterfor automatically taking up slack due to wear of the brake shoes and the like, so lthat brake cylinder piston travel may be maintained' substantially constant.,

The principal object of my invention is to provide an improved slack adjuster of the above character which is adapted tooperate positively to take -up the slack when the brake cylinder piston travel exceeds a predetermined amount regardless of Awhether the brake cylinder pressure is light or heavy. In the accompanying drawing; Figurel is an elevation of a bra-ke cylinder and slack adjuster apparatus vembodying my inven' tion, the controlling valve mechanism being' shown in section; Fig. .2 alsectional view ot the slack adjuster; Fig. 3 a tacev view of the slide valve. of the controlling valve mechanism; Fig. 4 a plan vieu' of the seat for said valve; Fig. -5 a sectional vi'ew of aportion of the controlling Valve mechanism in the position 'assumed when the brakes are applied and the travel of the brake cylinder piston exceeds the predetermined limit; and

Fig. 6 a sectional View ofa modified con-` struction of the controlling valve mechanism. l

`As shown-in Fig. 1, a brake cylinder 1 is provided having an air operated slack ad- 0 juster '2 and according to my invention, a

val-ve mechanism controls the fluid pressure for o ei'ating said slack adjuster.

The va ve mechanism 3 comprises connected pistons -1 and 5. the piston -1 being 5 preferably of larger area than piston 5, and

said pistons control a slide valve 1". The chamber 7 intermediate the pistons 4; and .3 is connected by a pipe 8 with a suitable source of fluid under pressure. such as the supplemental reservoir of a fluid pressure brake equipment.

The chamber 9 at the outer face of piston 5 is connected by a pipe 10 to a port in the brake cylinder 1, said port being located so that when. the brake cylinder piston travel exceeds a predetermined limit, said port is uncovered by the movement of the piston yand fluid from the brake cylinder is supplied to said pipe.

A diaphragm 11 in the casing of the valve mechanism is subject4 on one side'to the pressure of an adjustable spring 1Q and .the opposite side of the diaphragm communicates through passage 13 with the pipe 1t). The movement of diaphragm 11 is adapted to actuatel a valve 14 for: releasing tl-iiid ythrough a passage 15 fromchamber It-at the.r`

outer face of pistou 4.

The slide valve 6 has a cavity 17 adapted in one osition of the valvento connect pipe 1S leading to theslack adjuster 2 with pipe 19 leading to a reservoir 20. and *in another position said cavity is adapted to connect j In operation. the pressure in pipe 10 is normally atmospheric pressure. so that there y is atmospheric pressure in chambei on the piston 5, vand' as the outer face of the diaphragm 11 is subject to atmospheric pressure, the spring 1Q operates the diaphragm to permit the valve 14 to close. The piston 4 is provided with a small equalizing port 27 so that fluid under pressure. supplied from the source of pressure through pipe S to chamber T. equalizes into the closed chamber 16. The outer face of piston :'ibeing subjectto atmospheric pressure, the fluid pressure acting on the outer face ot'piston 4 operates to shift the pistons and valve 6 to the position shown in Fig. 1. in which pipe and acting oii the-diaphragm 11 operates the saine to open the valve 11i? Fluid is thereupon vented through passage` 15' from the chamloeii 'so that the unbalanced brake cylinder pressure in chamber l'operatesl the vpistons 4 and 5 to shift the valve 6 to the posit-ion shown/in Fig. 5,' in which carity 1T l inthe valve G connects pipe 18 with exhaust port 21. .The outer face-,of piston lis ythus that fluidunder pressure from the valve chai'nber T is admitted to the reservoii:20.

-Upon releasing-fthe brakes, pipey 10 isconnected to thef'latmosphere by. the :release movement of. .the brake.' cylinderf-piston, so

that diaphragm 11,",is moredby the-spring -12 to permit the, valve 14 to close.` Fluid equalizing into chainber`-16tlirough port 27 thereupon builds up .thepressure in said' `chamber and shifts the pistons to the position shown in Fig. 1, in which the ipe 19 is connected to pipe 18 by cavity 17. *luidundenpressureis then suppliedto piston 22 from therese-tiroir Q0 andsaid piston thereupon actuates the -pawl 241 which in turn opytoflhe brake I cylinder to valve 'chamber and valve Set connects pipe..

'crates the ratchet Wheel Q to rotatefthe screWV-QG and take up the slack.

If it is not desired to'employ the additional 'reservoirf1"20` the 'control-ling`|` rValve may be yconstructed asshown in Fig.'6. Ac-

cording to this construction, a casing 30 fis'` vprovided having a piston chamberA 31 containing afpiston and Aa val-ve chainber containing a slide Valve 34 adapted to be operated'byithe piston 32. The valve chamber isccniiectfed yto the supplylpipet and the vpressure iny the chamber at .the-outer face. of piston 3Q is-controlled by a valve 35. The valve 35 is operated by a diaphragm vtl'subject on one side -to the pressure lof'afspring 37 and oir the oppositeside l pressure supplied thereto through' pipe '10." Normally fluid equ'aliziiig froinpralve chain'ber'3-3 through portLS into' pistouchamber 31 maintains the fluid pressures on oppositesi'des of thetpiston 2in balance, softhatf'spring'39operates to lhold the pistoiil"in"the'ypositioii showvnpin Fig. tl.. in fivhicli pipe aiitlfpa oelSy is open l i phragm peln'gthe valve 35 and vent: 4fl'uid'ftliivre "-lOH'froin the piston chamber. pl,fr 'pressure in valve i if chamber 33 tliereuji'i 4 lthrough cavity '11 with exhaust port 1122. -Fluid is then re- 1a rig:

the piston I32 shitting the saule to the position `shown l'pon releasing the brakes, the tliiid pressure on diaphragm 36 is released and the ralre. 135 closes. 'The fluid pressures equalizing on opposite sides of the pistonBQ, the spring shifts the piston 32 and valve S13-l to the position shown inFig. 6, so that .fluid under pressure is admitted tothe slack adjuster piston. thus operating the same to take up the slack.

l'tavill now be apparent that with my im-A proved slack adjuster, the'sllack maybe taken up at any brake cylinder pressure suf- A ficient vto incre the brake cylinder piston beyond the slack''adjusterv port, as the brake cylinderpressure is not required ytodo the direct `work of taking up the slack, 'this pressure being merely the agentr for effecting thel operation of a valve mechanism for supplyii'ig fluid from another source to the slack'adjuster. Furthermore, the. slack is taken up on the release of the brakes, when there `is little or no resistance to the operation of the slack adjuster.

l Having non1 described my invention, what I yclaim as new and desire to secure by Letters Patent, is

leased from the slack adjuster` piston -22,

1. IThe co-inbinationjwith a pneiimatically'v operated slack adjuster, ofa valve' mechapliere and upon releasing' the brakes to admit fluid under pressure thereto.

2. The combination with apneumatically voperated slack adjuster, ofa valveinechav.-nisin adapted upon movement of the brake ,cylinder piston beyond -a predetermined point in applying the brakes to connect said'v slack adjuster4 with an exhaust' port and L;upon releasing the brakes to admit fluid un- .der pressure thereto to thereby actuate same and. take up the slack.

The combinati( y adapted to tal-ie up the slack upon the 'admissiaoiizof fluid under pressure thereto, of a falte mechanism for supplying fluid tov said slack adjuster uponl releasing the brakes.

l. T he combination with a slack adjuster 'adapted to take up the slack upon theadrnissiono'f. fluid under pressure thereto, of a valve mechanism for supplying fluid to said slack adjuster upon releasing the brakes ai, -ter an application of the brakes Where the travel of the-brake cylinder piston exceeds Ia predetermined amount.

5. The combinaton with a pneumatically controlled slacki adjuster, ot' a valve device for controlling the supply of tlu'id"`to said 1 slack adjuster and a valve mechanism Sub- -ject tothe opposing pressures of at'4 'spring and the brake cylinder for elfecting the operation .of said, valve devicef 6. The combination with i with a slack adjuster' a4r 'pneiimatically Y controlled slack adjuster, of a valve device for controlling the suppl of luid'to said slack adjuster, a movab e abutment .subject to brake cylinder pressure upon movement of the brake cylinder piston beyond a predetermined point in applying the brakes, and a valve operated by said-.abutment for varying the pressure on said valve device to effect the operation thereof.

7 L The combination With a pneumatically operated slack adjuster, of a valve for su plying. vand releasing fluid to and from sald vslack adjuster, a piston for operating same,

a movable abutment subject on one side to the pressure of a spring and on th'e opposite side to brake cylinder pressure upon movement of the brake cylinder piston beyonda predetermined point in applying' the brakes, and a valve operated byesaid movable abutmentfor venting air from said piston to thereby actuate the .supply 4valve for the lslack adjuster. l

8. The 'combination with a pneumatically operated slack adjuster, of a valve mechaf.

msm for supplying fluid to said slack adjuster and a reservoir adapted to be charged with fluid under pressure in one osition of said valve mechanism and adapted) to be con nected to said slack adjuster in another position' of said valve mechanism.

`the slack adjuster wit 9. The combination with a pneumatically operated slack adjuster, of. a reservoir and a valve mechanism operated by brake cylinderV pressure upon movement of the brake cylinder piston` beyond a predetermined point in applying the'brakes for charging said reservolr with fluid under pressure and adapted uponl releasing the brakes to connect said reservoir.

10. The combination with a pneumatically operated slack adjuster,- of a reservoir, a valvefada ted in one position to charge said reservoir Huid under pressure and in another position to connect said reservoir with the slack adjuster, a differential pistonprovided with two piston heads 'for operating said valve, a movable abutment subject to brake cylinder pressure in applying the brakesI upon movement of the brake cylinder piston beyond al predetermined point, and a. valve operated by said abutment for .venting air from one of said piston heads to thereby actuate said slack adjuster supply valve. I

.In testimony .whereof I have hereunto set my hand.

CHRISTOPHER P. CASS. Witnesses:

A. M CLEMENTS,

MARTIN. 

